Hurricane Michael
Hurricane Michael was a powerful and destructive tropical cyclone that became the first Category 5 hurricane to make landfall in the contiguous United States since Andrew in 1992. It was the third-most intense Atlantic hurricane to make landfall in the contiguous United States in terms of pressure, behind the 1935 Labor Day hurricane and Hurricane Camille in 1969. Michael was the first Category 5 hurricane on record to impact the Florida Panhandle, the fourth-strongest landfalling hurricane in the contiguous United States in terms of wind speed, and the most intense hurricane on record to strike the United States in the month of October.
The thirteenth named storm, seventh hurricane, and second major hurricane of the 2018 Atlantic hurricane season, Michael originated from a broad low-pressure area that formed in the southwestern Caribbean Sea on October 1. The disturbance became a tropical depression on October 7, after nearly a week of slow development. By the next day, Michael had intensified into a hurricane near the Guanahacabibes Peninsula, as it moved northward. The hurricane rapidly intensified in the Gulf of Mexico, reaching major hurricane status on October 9. As it approached the Florida Panhandle, Michael reached Category 5 status with peak winds of just before making landfall near Mexico Beach, Florida, on October 10, becoming the first to do so in the region as a Category 5 hurricane, and as the strongest storm of the season. As it moved inland, the storm weakened and began to take a northeastward trajectory toward the Chesapeake Bay, downgrading to a tropical storm over Georgia, and transitioning into an extratropical cyclone over southern Virginia late on October 11. Michael subsequently strengthened into a powerful extratropical cyclone and eventually impacted the Iberian Peninsula before dissipating on October 16.
At least 74 deaths were attributed to the storm, including 59 in the United States and 15 in Central America. Michael caused an estimated $25.1 billion in damages, including $100 million in economic losses in Central America, damage to U.S. fighter jets with a replacement cost of approximately $6 billion at Tyndall Air Force Base, and at least $6.23 billion in insurance claims in the U.S. Losses to agriculture alone exceeded $3.87 billion. As a tropical disturbance, the system caused extensive flooding in Central America in concert with a second disturbance over the eastern Pacific Ocean. In Cuba, the hurricane's winds left over 200,000 people without power as the storm passed to the island's west. Along the Florida panhandle, the cities of Mexico Beach and Panama City suffered the worst of Michael, incurring catastrophic damage from the extreme winds and storm surge. Numerous homes were flattened and trees felled over a wide swath of the panhandle. A maximum wind gust of was measured at Tyndall Air Force Base before the sensors failed. As Michael tracked across the Southeastern United States, strong winds caused extensive power outages across the region.
Meteorological history
A large area of disturbed weather spawned over the mid-to-western Caribbean Sea around October 1–2, and absorbed the remnants of Tropical Storm Kirk. The National Hurricane Center anticipated on October 2 that strong upper-level winds would prevent any significant development of the system for at least a couple of days. On the same day, a tropical wave an elongated trough of low air pressure tracked into the area. This possibly led to an increase in thunderstorm activity which in turn gave rise to a surface low southwest of Jamaica on October 3. Although the low was initially predicted to travel northward, it instead tracked west-southwestward and moved ashore in northeastern Honduras on October 4. The low became incorporated into a broad cyclonic gyre which was located over Central America by October 5. A center which was located over the eastern Pacific moved across Central America on October 6 and integrated into the gyre. The gyre's center reformed over the northwestern Caribbean Sea on the same day.Due to the imminent threat that the system posed to land, the NHC began issuing advisories on it as Potential Tropical Cyclone Fourteen around 21:00 UTC on October 6. Meanwhile, an upper-level trough located over the Gulf of Mexico was imparting vertical wind shear over the system. Despite this, the system's convection or thunderstorm activity, as well as its circulation, were improving in organization on both satellite imagery and in surface observations. The disturbance tracked generally northward within the southerly flow between a subtropical ridge which was located over the western Atlantic Ocean and a mid-latitude trough that was traveling eastward across the United States. A tropical depression spawned around 06:00 UTC on October 7, approximately south of Cozumel, Mexico. Around that time, Belizean radar showed that convection was forming just northeast of the depression's low-level center. The nascent depression was located in an environment of strong wind shear and warm sea surface temperatures. Around 12:00 UTC, the depression intensified into a tropical storm, receiving the name Michael. During the next six hours, the center of the storm relocated to the northeast as a result of flaring convection in that region. The system proceeded to travel slightly east of north as it rounded the western periphery of a mid-level ridge that was located over the western Atlantic.
After becoming a tropical storm, Michael began a period of rapid intensification. Initially, the NHC had predicted Michael to reach a peak intensity of as wind shear was expected to persist for at least two days, however, Michael became significantly stronger by the time it made landfall, reaching Category 5 status on the Saffir-Simpson scale. Two factors may have helped to facilitate the cyclone's intensification; the first was diffluence or streamline divergencethe elongating of a fluid body normal to the flow originating from an upper-level trough that was counteracting the wind shear. The second factor was that Michael's outflow entered another upper-level trough that was located east of the storm. A WC-130 aircraft from the United States Air Force Reserve 53rd Weather Reconnaissance Squadron discovered that Michael had been quickly intensifying as it surveyed the tropical cyclone in the afternoon and evening of October 7, measuring peak stepped frequency microwave radiometer winds between during its mission. Although Michael had strengthened to by 00:00 UTC on October 8, most of the storm's convection remained displaced to its eastern side as a result of the wind shear. Microwave imagery, however, showed that the core of Michael had improved, with one banding feature curving around most of the storm.
The tropical storm continued to organize, with convection and outflow increasing in the western half of the system. Michael became a Category 1 hurricane around 12:00 UTC on October 8. An eye was beginning to appear in satellite imagery around the same time. Around 18:30 UTC on October 8, Michael reached its initial peak intensity as a Category 2 hurricane with winds of as it tracked just west of Cabo del San Antonio, Cuba. But overnight, Michael's eyewall began to degrade due to a cold water eddy, dry air incursion, and wind shear, signaling that the rapid intensification had ceased. Shortly after, the hurricane's banding features began to improve as the system was located over the warm waters of the Gulf of Mexico. By 12:00 UTC on October 9, Michael had begun to rapidly intensify once more; its eye had become better defined and outflow improved as the westerly shear decreased. Meanwhile, the hurricane was tracking north-northwest due to a mid-level ridge. The tropical cyclone strengthened into a Category 3 major hurricane by 18:00 UTC as cold convection developed over the eastern and southeastern regions of the storm and wrapped around its eyewall. Cloud temperatures decreased to in the central dense overcast and were as low as in the eyewall.
Michael resumed a northward trek early on October 10 as it traveled between the ridge and a mid-latitude shortwave trough. Outflow generated by the trough may have hastened Michael's rapid intensification until landfall. The outer rainbands of Michael began to move ashore around 10:00 UTC, and the cyclone's eye continued to warm as it approached the Florida Panhandle, however, radar imagery showed a secondary eyewall was beginning to form. The hurricane's direction shifted to the northeast under the influence of the westerlies. Michael reached its peak intensity as a Category 5 hurricane with maximum sustained winds of and a minimum central pressure of around 17:30 UTC on October 10, as it made landfall near Tyndall Air Force Base in Florida. Operationally, the NHC had reported Michael's landfall intensity as based on flight-level winds of and SFMR readings between. However, some data from the SFMR instrument was missing and had to be reconstructed by the National Oceanic and Atmospheric Administration's Aircraft Operation Center. This data yielded a peak SFMR value of for the time that the reconnaissance aircraft surveyed the southern eyewall. Additionally, doppler weather radar from Eglin Air Force Base estimated peak winds of at 17:22 UTC, around the same location as the aircraft. The radar displayed that stronger winds existed northeast of the aircraft, outside its field of observation.
After moving ashore, Michael quickly became less intense; by 21:30 UTC on October 10, just four hours after landfall, Michael had weakened below Category 3 status before moving into southwestern Georgia. Around that time, the hurricane was continuing to track northeast under the influence of the westerlies. Doppler radar displayed that Michael had continued to degrade, with the storm weakening into a high-end Category 1 hurricane by 00:00 UTC. At that time, the peak winds were confined to a region of convection near Michael's low-level center. Six hours later, Michael fell to tropical storm intensity, with only a small zone of storm-force winds existing near its center. Most of the peak winds were displaced to the southeast, over the Atlantic Ocean. The storm entered South Carolina around 15:00 UTC on October 11. By that time, all of the gale-force winds associated with Michael were occurring over the Atlantic Ocean and along the shoreline.
As Michael entered North Carolina late on October 11, it began to transition into an extratropical cyclone. Cold, dry air entrained into the storm's circulation. Winds increased northwest of the storm's elongating center, over the states of North Carolina and Virginia. Michael became fully extratropical by 00:00 UTC on October 12 as it traveled east-northeastward, just north of Raleigh, North Carolina. Around that time, another low-level center with a lower pressure had formed farther north, near Chesapeake Bay, as baroclinic processes began to restrengthen the former hurricane. The extratropical cyclone emerged into the Atlantic around 06:00 UTC after passing near Norfolk, Virginia. Michael obtained hurricane-force winds on October 13 while in the Atlantic waters south of Nova Scotia and Newfoundland. It quickly traveled to the northeastern Atlantic by October 14. The cyclone turned sharply southeastward and later southward around the northeastern edge of the ridge, weakening slightly, as it approached the Iberian Peninsula. Michael's remnant low dissipated by 00:00 UTC on October 16, while it was located just west of northern Portugal. On the same day, Michael's extratropical remnant absorbed the remnants of Hurricane Leslie, which were situated to the east of Michael, following a brief Fujiwhara interaction; Michael's remnants subsequently dissipated shortly afterward.